COMPARATIVE STUDY OF IN VIVO STIGMASTEROL BIOSYNTHESIS IN NICOTIANA TABACUM AND HORDEUM VULGARE

Article abstract of DOI:10.1016/S0031-9422(00)83740-1

Key Word Index - Nicotiana tabacum; Solanaceae; tobacco; Hordeum vulgare; Gramineae; barley; phytosterols; stigmasterol; sitosterol.Six-day-old tobacco (Nicotiana tabacum) and barley (Hordeum vulgare) seedlings rapidly incorporated and metabolized exogenously supplied <4-14C>sitosterol but neither plant was able to convert it into stigmasterol.However, a sterol metabolite was isolated from both species and the acetate derivative was slightly more polar, on AgNO3-silica gel TLC, than stigmasteryl acetate.A similar metabolite was also obtained with <4-14C>cholesterol, indicating a general metabolic reaction of plants to exogenous sterols.Both species incorporated <2-14C>mevalonic acid into sitosterol and stigmasterol.We suggest that in vascular plants, whether monocotyledons or dicotyledons, the pathway of stigmasterol biosynthesis is not via sitosterol but through a common precursor which is derived from mevalonic acid.